The operational durability of fuel elements is largely determined by the quality of welded joints. Presently, fuel elements for fast-neutron reactors having casings made of high-chromium ferrite-martensite steels are sealed by the method of argon-arc welding (AW) with the use of a non-consumable tungsten electrode.
The known welded joint is comprised of the casing and the plug and has the butt-tool joint with the fusible shoulder arranged on the plug (see the book “Development, production and operation of fuel elements of power reactors” edited by Ph. G. Reshetnikov, vol. 2, Energatomizdat, 1995, pages 185-186, Table 20.1a). These welded joints use materials of the same grade, including high-chromium ferrite-martensite steels. The requirements for welded joints are defined in the Russian Industrial Standard OST 95 503-2006.
The main drawback inherent in welding of high-chromium ferrite-martensite steels is the tendency of these steels form quenching structures and cold cracks after a certain period of time upon completion of the welding.